Segment- A segment is a part of a line that begins at one point and ends at another. The points are called the endpoints of the segment.
external image segment_intersection.gifLINE
Endpoints: The point that starts a ray or segment
the dots on the picture are the endpoints external image f-345-15-ex-q.gif
Ray: A

ray

is a part of a line that start at a point and extends infinitely in on direction. A--------------->

external image geometry_homework_help_right_ray.GIF RAY
Angle: An angle is a figure formed by two rays with a common endpoint. Also common endpoints are callled vertex of angles and the rays are the sides of the angle
external image Right-angle.jpg
Vertex of an Angle: The point in common of the two rays that form an angle.
external image VertexAngle_1000.gif
Coplaner: Points are coplaner if they are all on the same plane.
Colinear: Points are colinear if one straight line can join them all.
external image parallel-lines-diagram.jpg
intersect: To have one or more points in common.
external image problem1_CCCCFF.jpg
line: The point that goes from one point and never ends.
<--------------------------->
Plane: Extends infinitely along a flat surface
external image Plane_1001.gif

Postulate 1.1.4
: Intersection of two lines is a point

Postulate 1.1.5: Crossing of two planes make a line
Postulate 1.1.6: Through any two points makes one line

Postulate1.1.7: Through any three points makes one plane

Points : When you look at the night sky and see the stars, the tiny dots of light seem like points. Points are often shown as dots, but unlike physical dots, geometry points have no size.Points are named by capital letters such as A or X.

Postulate 1.1.8- If 2 points are in a plane, then the line containing them is on a plane

A geometric line has no thickness,is a perfectly straight , and extendes forever. A line can be named by two points on the line, with a doubled-headed arrow over the two letters,or by a single lowercase letter.

Opposite Rays: have the same initial point, but extend in opposite directions
congruence-i-propositions_gr_194.gif
opposite rays

Intersect: one point in common.
Intersections: set of points in common.